Personal navigation systems for dismounted individuals (e.g., soldiers or firefighters away from their vehicles and vehicle-based navigational systems) can provide accurate satellite-based (e.g., GPS, GNSS) absolute position information in low-visibility areas (e.g., due to the presence of dust or fog) but may fail in remote areas where satellite-based positioning signals are obstructed or otherwise unavailable. Personal dead-reckoning systems may compensate for this by trying to determine, via pedometer counts or inertial measurement units (e.g., magnetic compasses, accelerometers, gyrometers), a current position relative to some absolute position. However, drift errors associated with inertial measurement units accumulate quickly, limiting the usable time of such systems to no more than 20 or 30 minutes. Longer-term accuracy may be achieved by the use of more sophisticated inertial measurement units (e.g., laser ring gyros), but such systems tend to be power-hungry, and too bulky for practical personal use.